The present invention relates to ball joint bearings, and in particular, to an improved all metal compression load ball joint utilizing a split upper bearing configured to provide a bearing surface for the top and sides of a ball stud, and to allow full engagement of the bearing with the housing and the stud simultaneously.
Conventional ball joints, and other movable sockets are used, for example, in automotive steering and suspension applications, and can be divided into two categories. The first category is for use in follower and tension load applications in which the stud member of the ball joint experiences axial tension loads, while the second category is for use in compression load applications in which the stud member of the ball joint experiences axial compression loads. Due to the different axial loads on the stud member, different ball joint designs are required for each category, which are generally not interchangeable.
In general, ball and socket joints comprise a cylindrical housing having a cylindrical internal surface and an opening through which the shank portion of a stud member extends. A ball end portion of the stud member is contained in the housing, with one or more bearing members supporting the ball end portion within the housing. Traditionally, the bearing members are composed of a synthetic resin, such as a polymer or elastomer, or a sintered alloy. These components are installed into the housing through an opening, with the ball stud extending outward through an axially disposed opening which may either be the same opening through which the components were installed, or an axially opposite opening. Conventionally, tension load ball joints, such as the M2 Technology chassis parts available from the Moog Chassis Parts division of Federal Mogul Corporation, utilize two openings at opposite ends of the housing. After the components are installed therein, one opening is closed by means of a cover-plate, spun, swaged, or welded in place, and the stud member extends outward through the opposite opening. Once secured in place, the cover-plate presses on the bearing members either directly or indirectly through a resilient rubber intermediate component.
In contrast, compression load ball joint housings, such as shown in U.S. Pat. No. 6,010,271 to Jackson et al., have only a single opening through which all the components are installed during assembly, and through which the stud member protrudes. These components include a compression spring, a polymeric lower bearing, the stud member, and a metal upper bearing. Once the components are in place, and the stud member shank is protruding from the opening, the peripheral edges of the opening are swagged or rolled to retain the components in place and compressing the spring.
Once assembled, ball joints and movable sockets may be utilized as load carrying members in numerous mechanical systems, including automotive vehicle suspension and steering systems. Movable sockets or ball-joints employed in these applications are subjected to various operating conditions, and may be required to carry substantial loads. When wear develops, particularly in polymeric bearings, the performance of the movable socket or ball-joint rapidly degrades and, in the case of automotive applications, may result in erratic steering or excessive looseness and play in the vehicle suspension system.
Accordingly, it is desirable to provide a compression load ball and socket joint having an improved resistance to wear.